Brush holder having a minimal number of parts

ABSTRACT

A brush holder arrangement for holding an electrical brush in position for contacting conducting portions of rotating electrical machinery or the like, characterized by the simplicity of the holder and the rapidity with which a brush can be installed in operative position, and appropriate electrical connections made thereto.

United States Patent Schaffer Aug. 5, 1975 15 BRUSH HOLDER HAVING A MINIMAL 2,382,799 8/1945 Leach et a1. 310/247 NUMBER OF PARTS 3,247,408 4/1966 Rebechini lilo/247 3,339,098 8/1967 Burrows ct a1. t. 310/239 Inventor: Richard Schaffer, Ocala, 3,387,156 6/1968 Elow et a1 I 310/242 Assigneez The Bison p y, Ocala, Fla 3,436,578 4/1969 Walter 310/242 [22] il i Jl-l 1973 Primary Examiner-J. D. Miller Assistant ExanzinerPatrick R. Salce l A 1.N .:374,89 [2 I pp 0 9 Attorney, Agent, or Firm.1ulian C. Renfro, Esq.

[52] US. Cl. 310/247; 310/239; 310/242 [51] Int. Cl. H0lr 39/40 [57] ABSTRACT [58] Field of Search 310/247, 239, 249, 242, A brush holder arrangement for holding an electrical 310/87; 339/69 brush in position for contacting conducting portions of rotating electrical machinery or the like, characterized [56] References Cited by the simplicity of the holder and the rapidity with UNITED STATES PATENTS which a brush can be installed in operative position,

and appropriate electrical connections made thereto. 1,401,679 12/1921 Dillin 310/249 2,194,620 3/1940 Sekyra 310/247 4 Claims, 4 Drawing Figures PATENTED AUG 5|975 HG.1A

FIGS

1 BRUSH HOLDER HAVING A MINIMAL NUMBER or PARTS BACKGROUND OFTHE INVENTION The use of small, brush-typeuniversal meters is quite extensive. with the major application being small household appliances. In the manufacture of such appliances, competition is very severe and everyattempt must be made by the manufacturer to minimize production costs. Due to the high volume production of these motors, even a few cents saved in materials or a few minutessaved in assembly time can have a very significant impact on the manufacturers competitive position in the market place. I

As will be seen hereinafter, the presentinvention 'relates to the design, construction, and assembly of the electrical brushes used on series-type moto rs,and more particularly to an improvement in the connections between the motor winding leads and the electric motor brushes.

In endeavoring to simplify the mechanical configuration, to reduce the number of parts, and to reduce the time of assembly of such devices, a new and novel structure has been achieved.

FIELD OF THE INVENTION This invention relates to an electrical brush' holder for electrical motors, generators and the like having commutators or slip rings and an improvement thereto involving the interconnection between electrical brushes in such holders and the associated apparatus windings, wiring and the like. This invention also relates to the method of installing, assembling and interconnecting of such electrical brushes.

DESCRIPTIQN OF T E PRIo ART similar methods. Therefore, all known prior art devices.

require at least the two separate assembly operations of (l) installing or assembling of the brush in its holder, and (2) performing a separate mechanical operation of attaching the required wire lead or leads to an electrical connection to the brush.

SUMMARY OF THE INVENTION This invention relates to a novel structure and method for interconnecting external wiring with an electrical brush that requires fewer parts, less material, and fewer assembly operations than devices in the prior art. A typical structure of this invention consists of a body member or housing of insulating material to be mounted in the frame of a motor or other electrical device, which body memberor housing has a tubular portion therein. This tubular portion may be defined by a metal barrel designedto hold an electrical brush in its preferred position for contact with a commutator, slip rings, or other movable electrical contact. A. threaded cap screw fits into threads in the non conductive body immediately adjacent to the end of the metal barrel. In accordance with this invention, channel means in the form of a groove or slot are provided longitudinally in one side of the threads to accept an insulated interconnection. wire having its end stripped of insulation. If a groove is used, it is of such depth that the insulated wire does not interfere with the insertion of the cap screw. The brush utilized in accordance with this invention typically is equipped with a pigtail wire and light compression spring, with a contact disk being attached to the wire and spring at a location remote from the brush itself.

In assembly of the structure, the brush including the pigtail wire and light compression spring are inserted into the tubular portion. The contact disk is pushed down through the threads of the body portion, and against the end of the metal barrel, thereby compressing the spring. The interconnection wire is inserted so that the insulated part lies in the groove, whereas the bared end is bent to lie on the contact disk. The cap screw is then inserted in the body threads and tightened to securely clamp the bared wire against the disk, which is in turn clamped against the end of the metal barrel. The compression spring is thus maintained in a compressed condition, such that it maintains required brush pressure on the commutator or other electrical contact.

As will be apparent, this invention makes rapid assembly possible, and eliminates the requirements for soldering lugs, crimped devices, screws or other separate devices for attaching the interconnection wire to the brush. Furthermore, the operation of attaching the interconnection wire to the brush is accomplished essentially simultaneously with installation of the brush cap screw, thereby eliminating the labor and time to perform separate operations as required by prior art devices.

It is therefore a principal object of this invention to provide a novel electrical brush holder and interconnection means having fewer parts and less material than prior art devices.

It is another object of this invention to reduce the labor and time required in the assembly of a device utilizing electrical brushes by elimination of such operations as soldering, welding, crimping, and screwing in forming the interconnection of the electrical brushes with other parts of the device.

It is a further object of this invention to provide an improvement in the design of prior art electrical brush holders to reduce the cost of the holder and the cost of assembly in applicable equipment.

These and other objects, features and advantages of this invention will be more apparent from a study of the appended drawings in which:

FIG. 1 is a sectional view of the brush holder body for a typical brush holder in accordance with my invention; I FIG. 1A is a plan view of the brush holder body of FIG. 1;

FIG. 2 illustrates a brush inserted in the brush holder body, and depicts in exploded relation the interconnection wire prepared for installation, and the cap screw for compressing the brush spring and for clamping the interconnection wire; and

FIG. 3 is a sectional view of a completely assembled brushholder in accordance with this invention, showing the cap screw holding the interconnection wire clamped against the brush contact disk, and the brush biased against a commutator.

DETAILED DESCRIPTION Turning now to the figures of drawing, it will there be seen that I have depicted a brush holder arrangement for holding an electrical brush in an appropriate position for contacting conducting portions of rotating electrical machinery of the like. The brush holder comprises a housing or body 2 typically of insulating material, such as phenolic with the body having therein a tubular portion 3 of such configuration that a brush 7 of graphite or the like can be inserted in the open end of the tubular portion. The tubular portion is preferably rectangular in cross section, as generally indicated in FIG. 1A, with the brush 7 being slidably received therein. The lower or active end of the brush 7 is ordinarily spring biased into contact with the rotating electrical component, such as commutator 14 in the manner revealed in FIG. 3. The body portion 2 is typically mounted in a support such as a motor housing 6, and held therein by a mechanical arrangement that may for example include a bracket 16 and screw 17.

The brush 7 has'a metallic contact disk 9 to which it is electrically connected such as by a pigtail lead 8, with the disk being of a size to fit atop the open end of the tubular portion, such as upon a shoulder 18. The tubular portion may be a metallic component separate from but contained in the body 2, as revealed in the figures of drawing. In this instance, when the brush 7 is disposed in the metallic tubularportion, the disk 9 may be easily positioned in electrical contact with such metallic portion.

As will be noted from the figures, a portion 2a of the body or housing extends beyond the open end of the tubular portion 3, with this housing portion being somewhat enlarged, concentric with the tubular portion 3, and equipped with threads at a location closely adjacent the open end of the tubular portion. A threaded cap 13 is arranged to be threadedly received in the threads 5 of the housing portion, as revealed in FIG. 3, with the threaded cap being larger in diameter than the contact disk 9.

In accorance with this invention, a groove or slot 4 is formed in the housing portion at a location where the housing portion enlarges, with this groove cutting essentially transversely across the threads 5 as perhaps best revealed in FIGS. 1, 1A and 2. Quite significantly, the groove 4 is of a depth that an insulated electrical wire, such as the wire 11 shown in FIGS. 2 and 3 can reside therein without interfering with the cap 13 being threadedly received in the threads 5 of the housing portion.

Turning now to FIG. 2, other components associated with my invention may be seen in some detail. In this view, the brush 7 is shown in approximately its normal operating position in the tubular member 3. At the top end of brush 7 as shown is a pigtail wire 8, with one end thereof being attached to the brush, and the opposite end of this wire being conductively attached to disk 9. A spiral compression spring 10 is disposed between the contact disk 9 and brush 7 as shown in FIG. 2 so as to maintain a light tension on pigtail wire 8 when the brush is not installed and for forming after installation a spring bias that holds the active end of the brush against the commutator 14.

It will be noted from FIG. 2 that a short length of insulation has been removed so as to form a bare end 12 on the interconnection wire 11. This figure of drawing illustrates a preferred length of the bared portion of this wire relative to the scale of the drawing. The threaded cap screw 13 shown above the wire 11 may be metal if the motor design poses no insulation requirement at this point, or it may be of a hard insulating material if desired.

FIG. 3 illustrates the completely assembled brush holder with the interconnection wire 11 in place. As may be noted, the interconnection wire 11 has been inserted in groove 4 such that insulation extends approximately half way toward barrel 3 and the bare wire 12 makes contact with and lies on top of contact disk 9. Cap screw 13 is now tightened down to securely clamp bare wire 12 against contact disk 9, which disk is in turn clamped against the shoulder 18 created at the juncture of the tubular opening and the bottom of the threads 5. As a result of this arrangement, the wire end 12 is caused to make a positive electrical connection to the contact disk 9, as well as to be anchored tightly there against in a mechanically secure fashion. Also, it should be noted that if a metallic member is utilized to form the tubular portion 3, the disk is caused to form an electrical contact therewith, as shown in FIG. 3.

Further, the tightening of the disk in the threads 5 causes a compression of the spring 10, which in turn biases the active end of the brush 7 into effective electri- I cal contact with the commutator 14.

A method of assembly may best be understood from FIG. 2, which reveals the body or housing member already secured in place in the motor housing 6. By way of preparation, the operator strips the insulation from wire 11 and bends the bare end 12 at approximately a right angle. He inserts brush 7 into barrel 3 and then with a finger or suitable tool, pushes disk 9 against the shoulder 18 at the top end of barrel 3, thus compressing spring 10. He then places wire 11 in grove 4, utilizing bent bare end 12 to temporarily maintain pressure on disk 9 so that the finger or tool can be removed. The operator thereafter engages the threads of cap screw 13 in body threads 5 and tightens cap screw 13, thereby clamping bare wire 12 securely and conductively against contact disk 9, which in turn is clamped against metal barrel 3 if such is used. The spring 10 is now maintained in a compressed condition.

While I have shown a certain style of brush holder in order to illustrate my invention, it is within the scope of my invention to provide channel means in the form of a groove, slot or hole in the body of a holder such that an insulated interconnection wire having a bared end can be inserted and the bared end then clamped against a disk or brush-holding barrel by a screw or plug that also provides compression of the brushing spring. For example, variations may include brush holders which do not utilize a pigtail connection to the brush, but rely on contact between brush and metal barrel. In this latter example, the spring compression screw clamps the interconnection wire bared end against the metal barrel either directly or through the disk, thus forming the required electrical connection. On the other hand, a brush holder could have the tubular portion that slidably receives the electrical brush formed by the insulated body member without the employment of a metal barrel, but of course in this instance an electrical connection in the nature of a pigtail lead or the like would be a necessity.

As should now be apparent, an experienced operator can assemble the brush in its holder and make the required electrical connections thereto with fewer steps or operations, and with a minimum number of tools being involved, than necessitated by the prior art, thus considerably reducing the time required for this phase of assembly of an electrical device.

I claim:

1. A brush holder for holding an electrical brush in position for contacting conducting portions of rotating elelctrical machinery or the like, comprising a housing having a tubular portion, said tubular portion having an open end and having an inner configuration such that a brush is slidably received therein, said brush having a metallic contact disk to which it is electrically connected, said disk being of a size to fit atop said open end of said tubular portion at such time as said brush is disposed in said tubular portion, a portion of said housing extending beyond the open end of said tubular portion, said housing portion being threaded at a location closely adjacent said open end of said tubular portion, a threaded cap screw arranged to be threadedly received in the threads of said housing portion and being larger in diameter than said disk, a groove in said housing portion, cutting essentially transversely across the threads thereof, said groove being of a depth such that an insulated electrical wire can reside therein without preventing said cap screw from being threadedly received in the threads of said housing portion, the insulated wire having a stripped end adjacent said disk, such that a portion of bare electrical wire can be clamped against said disk by said cap screw, so as to make good electrical contact with said disk and therefore said brush, as a result of the tightening of said cap screw.

2. The brush holder as defined in claim 1 in which said tubular portion is metallic.

3. The brush holder as defined in claim 1 in which said brush is connected to said disk by a pigtail lead, and is spring biased in a direction away from said open end of said tubular portion.

4. In a brush holder for holding an electrical brush equipped with a pigtail wire in position for contacting a movable electrical contact, a contact disk connected on the end of the pigtail wire remote from said brush, a compression spring disposed between said contact disk and brush end, the brush being slidably carried in a metal barrel contained in a body of insulating material, said body having a threaded hole concentric with the barrel and adjacent to the end thereof, the threaded hole accepting a threaded cap screw that holds said contact disk against the inside end of the barrel, thereby compressing the brush spring to hold the brush in firm contact with the movable contact, the improvement comprising a groove disposed longitudinally in the threads of said threaded hole, said groove having a depth for accepting insulated interconnection wire without interference to said cap screw, whereby a stripped end of said insulated wire can be clamped between said cap screw and said brush contact disk, thereby providing positive electrial connection to said electrical brush. 

1. A brush holder for holding an electrical brush in position for contacting conducting portions of rotating elelctrical machinery or the like, comprising a housing having a tubular portion, said tubular portion having an open end and having an inner configuration such that a brush is slidably received therein, said brush having a metallic contact disk to which it is electrically connected, said disk being of a size to fit atop said open end of said tubular portion at such time as said brush is disposed in said tubular portion, a portion of said housing extending beyond the open end of said tubular portion, said housing portion being threaded at a location closely adjacent said open end of said tubular portion, a threaded cap screw arranged to be threadedly received in the threads of said housing portion and being larger in diameter than said disk, a groove in said housing portion, cutting essentially transversely across the threads thereof, said groove being of a depth such that an insulated electrical wire can reside therein without preventing said cap screw from being threadedly received in the threads of said housing portion, the insulated wire having a stripped end adjacent said disk, such that a portion of bare electrical wire can be clamped against said disk by said cap screw, so as to make good electrical contact with said disk and therefore said brush, as a result of the tightening of said cap screw.
 2. The brush holder as defined in claim 1 in which said tubular portion is metallic.
 3. The brush holder as defined in claim 1 in which said brush is connected to said disk by a pigtail lead, and is spring biased in a direction away from said open end of said tubular portion.
 4. In a brush holder for holding an electrical brush equipped with a pigtail wire in position for contacting a movable electrical contact, a contact disk connected on the end of the pigtail wire remote from said brush, a compression spring disposed between said contact disk and brush end, the brush being slidably carried in a metal barrel contained in a body of insulating material, said body having a threaded hole concentric with the barrel and adjacent to the end thereof, the threaded hole accepting a threaded cap screw that holds said contact disk against the inside end of the barrel, thereby compressing the brush spring to hold the brush in firm contact with the movable contact, the improvement comprising a groove disposed longitudinally in the threads of said threaded hole, said groove having a depth for accepting insulated interconnection wire without interference to said cap screw, whereby a stripped end of said insulated wire can be clamped between said cap screw and said brush contact disk, thereby providing positive electrial connection to said electrical brush. 